Astragalus Polysaccharide Nano-Liposomes Modulate the Inflammatory Response and Oxidative Stress in Stroke-Associated Pneumonia by Increasing OIP5-AS1 to Regulate the miR-128-3p/SIRT1 Pathway

Abstract

Stroke-associated pneumonia (SAP) is major reason for the poor prognosis of stroke patients. Astragalus polysaccharide (APS) is a commonly used Chinese herbal extract that regulates the inflammatory response, however, its therapeutic effects on APS as well as its underlying mechanism of action are unclear. In this study, we evaluated the effects of APS nano-liposomes on SAP, including regulation of the inflammatory response and oxidative stress, as well as the underlying molecular mechanism. Serum samples of SPA were collected from patients and healthy controls and the expression of OIP5-AS1 and miR-128-3p was measured. Lipopolysaccharide (LPS) was used to construct an in vitro lung injury model using RLE-6TN lung epithelial cells and APS nanoliposomes were used for treatment. Several cellular processes were evaluated including OIP5-AS1, miR-128-3p, and SIRT1 expression by RT-PCR, SIRT1 protein expression by western blot analysis, IL-1β, TNF-α, and IL-6 expression by ELISA, a bioinformatics analysis for downstream molecular targets of OIP5-AS1, and dual luciferase and RNA immunoprecipitation (RIP) assays to identify interactions between miR-128-3p, OIP5-AS1, and SIRT1. Our results revealed low expression of OIP5-AS1 and high expression of miR-128-3p in SAP. Treatment with APS nano-liposomes reduced LPS-induced apoptosis of RLE-6TN cells, inhibited the inflammatory response and oxidative stress, and increased OIP5-AS1 and SIRT1 expression. Furthermore, the overexpression of miR-128-3p reversed the protective effect of APS nano-liposomes on LPS-induced RLE-6TN cells. In summary, OIP5-AS1 is an endogenous competitor that inhibits miR-128-3p targeting of SIRT1. APS nanoliposomes significantly reduced miR-128-3p expression resulting in increased OIP5-AS1 expression.